Henry s



(No Model.)

H. S. THORNBBRRY.

TELEPHONE TRANSMITTER.

No. 321,328. Patented June 30,1885.

UNITED STnTns PATENT @rrrcn.

HENRY S. THOENBERRY, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO THE AMERICAXBELL TELEPHONE COMPANY, OF SAME PLACE.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 321,323, dated June 30,1885. Application filed July 5, 1884. (No modelJ To all whom it mayconcern:

Be it known that I, HENRY S. THORNBERRY, of Boston, in the county ofSuffolk and State of Massachusetts, have invented certain improvementsin TelephoneTransmitters, of

which the following is a specification.

The object .of my invention is to improve the construction and to rendermore popular and effective that form of batterytransmitter in whichparticles of conducting material, in

a loose or free state, form the current-regulating medium.

The transmitter described in United States Letters Patent granted toHenry Hunnings,

1 No. 250,250, November 29, 1881, is of this class. In the practicaloperation of that transmitter ithas been found desirable in attainingthe best results to hold the transmitter at a certain angle between thehorizontal and vertical, and it has also been found that after suchtransmitter has been in frequent use the particles become moist andsticky. This is due, it is believed, to the moisture from the i breathof the operator, which reaches the par- 2 5 ticles around the edges ofthe diaphragm, the edges being, as customary, left freethat is to say,not permanently fastened to its seat, as by solder, but merely heldagainst the same by greater or less pressure. In the ordinary o Hunningstransmitter, such as imported into this country, a circular chamber ismade in a block of insulating material which contains the looseconducting particles. Above the latter is a very thin platinumdiaphragm, and upon this a brass plate having a number of small holes.lVhen the sievelike brass plate is omitted, which is an improvement, andonly the thin platinum diaphragm used, the rotating rubbing movement ofthe cap 0 which holds it down frequently wrinkles the edge of the disk,leaving-a passage sufficient for the moisture to reach the carbonparticles. Sometimes a few of these particles will find their waybetween the disk and its seat and 5 prevent the latter from lyingperfectly fiat. Thus, in one way or another, it will happen that ifmoisture is permitted to reach the disk it will find its way behind it.To obviate these diiiiculties I rigidly fix the chamber con lining thevariable resistance of my transmitter at that angle from the horizontalin practice found most desirable, which angle might be slightly varied,and I place before the diaphragm a curved metal trumpet or mouthpiece,against the sides of which any moisture will strike and be precipitated,

My invention further consists in placing the vibrating diaphragm underthe mass of conducting medium, or, inother words, placing the particlesof conducting material on the diaphragm, where they are normally held bygravity and rendered more sensitive to soundvibrations than was formerlythe case. I furtherimprove the effectiveness of the instrument by usinga damper of a substance such as a thin sheet of rubber, cork, or animaltissue placed outside of the platinunrfoil diaphragm commonly in use.

My invention also consists in rendering the chamber in which theconductingparticles are confined adjustable, and in certain details ofconstruction, to be described.

In the accompanying drawings, Figure 1 shows my transmitter complete.Fig. 2 shows a section of the trumpet, containing-chamber, and operativeparts. Fig. 3 shows a modification. Fig. 4 shows details ofconstruction.

T is a metal trumpet or mouth-piece curved and arranged, substantiallyas shown, so that the particles of moisture conveyed thereto from themonth in speaking (such particles moving in straight lines) will strikethe further side of the tube and be precipitated or retained and theconducting material will not be affected. Metal is the preferredmaterial for the trumpet because, being a. better conductor of heat thanwood, rubber, and other substances, the moisture will readily condenseupon it. The upper end of Tis screw-threaded to receive a screw-thread,c, on the contain- 9 ing-chainber 0, preferably formed from somenon-conducting substance, as vulcanized rubher.

0 is a collar firmly fixed to chamber 0 and screw-threaded to receive ametal ring, r.

S is a screw-plunger, the head of which enters the chamber N, whereinare placed particles of finely-divided conducting material a, asgranulated retortcarbon. The enlarged end of S may be projected more orless into 109 chamber N to regulate the size of said chamber. Uponplunger S is fixed a set-screw, s,

to which one end of the battery-circuit is connected. The object of thisconstruction is to enable the size of the containing-chamber for thefinely-divided material to be changed at will. In transmitters of thisclass the best results .are obtained by filling the chamber abouttwo-thirds full. Sometimes, however, a high normal resistance isrequired, and consequently a larger quantity of carbon or otherparticles are needed in the chamber. By turning the set-screw s in theproper direction the plunger S can be withdrawn, so as to enlarge thesize of the chamber to admit the increased amount of conductingparticles.

Over the aperture in ring ris placed a platinum diaphragm, p,andbetweenthis platinum diaphragm and the aperture of ring 1", I place adamper consisting of a thin sheet of animal tissue of a flexible nature,as d,- or it may bea thin sheet of rubber or cork,which I affiX to theplatinum diaphragm by a drop of some adhesive substance, as sealing-wax,placed at or near the center thereof;

To avoid the possibility of injuring or changing the form of the damper,I place athin washer, w, Fig. at, outside thereof, against which thesurface of ring rwillturn in screwing it on.

Instead of fixing the damper d to the diaphragm p by some adhesivesubstance, the damper and diaphragm may be held in contact by anadjustable spring, as a.

Around the inner orifice of the trumpetT a shoulder, as y, is turned up,against which the metal ring r presses when in position. The second endof the battery'circuit is connected to trumpet T, as at t, circuitpassing via elements t T y r p, conductingparticles n, S, and s. Thiscircuit may be the main circuit and battery or a local circuit andinduction-coil, as is well-known. It will be noticed that at all pointsthis circuit is of sufficient conductivity to avoid heating by anyordinary battery.

The apparatus so constructed is placed in position substantially asshownin Fig. 1. The case B is formed and intended-to be placed firmly inposition, as upon a wall, and the location of trumpet T is such that theplane of either or both walls of the chamber N will be at an angle fromthe horizontal, preferably of from twenty to thirty degrees, this beingfound in practice the most advantageous position, since in this positionit is believed that the conducting particles are not so likely to packor solidify.

The operation of my transmitteris similar to others of its class.

What I claim, and desire tosecure by Let ters Patent, is-

1. A telephonic transmitter comprising a mass of finelydividedconducting particles confined and resting upon a diaphragm located at anangle between a horizontal and perpendicular.

2. In a telephone-transmitter, an adjustable chamber containingparticlesof finely-divided conducting material resting upon a flexible diaphragmfixed at an angle between a horizontal and perpendicular.

3. In a telephonic transmitter wherein the means forvaryingthe circuitconsists of a mass of finely-divided conducting particles, a chamber forcontaining such particles, and having means for regulating the size ofsaid chamber to admit of a greater or less quantity of such particles.

4. The combination, in a telephone-transmitter, of a mass offinely-divided conducting material resting by gravity upon a metallic:

diaphragm, a damper consisting of a disk of animal tissue, cork, rubber,or similar material cemented to thediaphragm at or near its center, andclamped thereto at its periphery by a perforated cap or ring, with anintervening ring or washer to prevent displacement of the damper,substantially as described.

5. An electric telephonic transmitter comprising a mass offinely-divided conducting particles confined and resting upon adiaphragm located at an angle between a horizontal and perpendicular,and a damper consisting of a thin sheet of animal tissue, rubber, cork,or other like material.

6. The combination, in a telephone-transmitter, of an inclosin g chambercontaining finely-divided conducting material resting upon a metallicdiaphragm, with a damper consisting of a disk of animal tissue, cork, orrubber cemented to the diaphragm at or near the center thereof.

7. In a telephonic transmitter, the combination of a chamber forcontaining the currentvarying medium, means for varying the size of saidchamber, a flexible metallic diaphragm upon which the said mediumnormally rests by gravity, a mouth-piece, and an inclosing-case, thewhole arranged to permanently retain the diaphragm at an angle between ahorizontal and perpendicular, substantially as described.

8. In a telephonic transmitter, the combination of the chamber 0,adjustable plunger S, conducting particles n, diaphragm p, damper (1,and trumpet or mouth-piece T.

In testimony whereof I have signed my name to this specification,in thepresence of two sub: scribing witnesses, this 28th day of June, 1884.

H. S. THORNBERRY.

\Vitnesses:

WM. 13. VANSIZE, GEO. VVILLIs PIERoE.

